This invention relates to a flexible composite sheet suitable for use as a liquid-pervious top material in a disposable body fluid absorbent sanitary article such as a disposable diaper, a sanitary napkin and the like.
Japanese Patent Application Publication No. 1999-217453A describes a flexible composite sheet comprising a sheet-like fibrous assembly having upper and lower surfaces and a flexible plastic sheet bonded to the upper surface of the fibrous assembly. The plastic sheet including a plurality of flat zones extending parallel one to another in one direction each having a thickness of 0.001xcx9c0.05 mm and a width of 0.03xcx9c1 mm and a plurality of opening arrays each defined between each pair of the adjacent flat zones and comprising a plurality of openings arranged intermittently in the one direction. Each pair of the adjacent flat portions with the opening array lying therebetween are connected to each other by bridge-like portions extending across the opening array. The respective flat portions include tooth-like portions extending upward from their upper surfaces. The upper surface of the fibrous assembly is exposed through the respective openings.
When the known composite sheet is used a top material to cover a liquid-absorbent core of an article, for example, a disposable diaper or a sanitary napkin, excretion such as urine, loose passage or menstrual discharge is apt to stay on the flat portions of the plastic sheet without being rapidly absorbed by the core.
It is an object of this invention to provide a composite sheet designed so that excretion discharged on such sheet may be rapidly absorbed by the core.
According to this invention, there is provided a flexible composite sheet comprising a sheet-like fibrous assembly having upper and lower surfaces and a plurality of thermoplastic synthetic resin lamellae each having an upper surface and a lower surface and being bonded to the upper surface of the sheet-like fibrous assembly so that the upper surface of the fibrous assembly is exposed through a gap defined between each pair of the adjacent lamellae.
The flexible composite sheet further comprises each of the lamellae being formed on the upper surface thereof with a plurality of grooves extending parallel one to another and each of the grooves extending from one side edge of the lamella to the other side edge of the same lamella opposed to the one side edge.